Help, it will not start! Roush 427sr with MSD
 

I hope someone can help. I have a roush 427sr/tw. It will not fire, plenty of fuel. Initial investigation found the MSD distributor cap button eroded away, on the MSD distributor. The cap was replaced with the rotor paddle bent up to ensure contact. All spark plug wires under 1200 ohms. The car has the ford duraspark and factory coil. I replaced both the coil and the duraspark module. No start. Both the new and old coil had the same primary resistance of 1 ohm and secondary resistance of 10K ohms. I am pretty sure it is not the coil.

I checked voltage at the coil connection, with it disconnected I get 11 volts with it conected to the coil I get nothing even when cranking the engine. I checked the resistance in the distributor magnetic pickup and it was 900 ohms in the middle of the allowed 400 to 1300 ohm range. Since I am getting voltage at the coil connection when not connected to the coil I would assume I should get a spark to jump out of the coil wire.

Is there any other checks to verify the magnetic pickup is working besides resistance? I assume since I am getting voltage at the coil connection bracket the ignition module is working.

Any ideas? Car was running perfect drove it all day, went for one last ride and it would not start in the garage.

I appreciate any help!!!

I know with a MSD module, to check the pick-up, you can touch the wires from the module going to the distributor, and that should cause a spark. I donl;t know if that will work with the duraspark module though.

No Start
 

I Had Same Problem With A Ford And It Was The Dura Spark I Had It Checked And It Was Failing So Have It Tested Napa Auto Parts Tested Mine At No Charge
Len

Funny thing is I purchased a new one and plugged it in with no sucess. I also verified that the two wires that connect to the msd distributor plug have no voltage across them. I guess it is possilbe I have two bad durasparks. I wonder if the resistance across the mag pickup should vary as the distributor turns. Does anyone know the theory behind how it provides feed back to the control module.

Ok, the magnetic pickup in the distributor induces a voltage as the finger wheel rotates past it, crossing flux lines, this is the signal sent back to the control module. Granted it is millivolts but at this point I am confident the magnetic pickup in the distributor is working.

I may very well have another bad duraspark. I will see how to test it.

The resistance across a MSD Magnetic Pickup is 300-1300 OHMS...
Disconnect wires and check...

Well, I might be a bit late to the party, but:

Okay, in the simplest of operation, 12V to one side of the coil and momentary touching of the other side of the coil ( negative ) to ground will jump the spark and tell you if the coil is working. Then you might want to turn on the ignition and touch the negative side to ground momentary and see if you get a spark, if yes, the ignition is working.

Then open the distributor and turn over the engine and make sure the rotor turns.

I would then suspend the coil wire from the coil over a ground and see if you get any spark. No spark?

Remove the any "ignition boxes" and run the distributor old style to remove the distributor and ignition setup from the problem.

Old style is 12v ( controlled by the ignition switch ) to a .82 Ohm resistor, then the resistor to the positive side of the coil. The negative side goes to the distributor.

There are two problems that come up more than others, good ground and good 12V.

I hope this helps or spurs another idea to fix it.

:D :D

It checked fine at 900 ohms.

Thanks,

I tried the 12 volts to positive side of coil and gnd to other and big spark, then duplicated with ignition. so ignition is working, it appears distributor pick up is working, last alternative is to get 3rd duraspark and plug in to see if it works.

Try unpluging the distributer and put an analog volt meter between the two conections on the wire from the distributor, on the miliamp scale. The needle should move as the motor is spun with the starter. If not replace the magnetic pickup. I have seen the magnent in the pickup cracked and it didn't produce enough voltage to activate the duraspark.

OR
See if Pertronix makes a pickup unit that fits in your MSD Distributor. Then you will be able do away with the Duraspark.

I might be wrong, but it was my understanding that Roush engines require an ignition (MSD) box with a 6000 chip installed for their 2 year warranty. I might be wrong!!! but I remember reading that or was told that when I purchased my 402r from Todd @ Roush.

I have read their warranty papers back and forth no written request of rev limiter, they do indicate ase certified mechanic to install in order to maintain warranty.

I checked the mag pickup and it is fluctuating 1 milliamp so it appears it is good. Have not had time to work on it lately hope to get back on this weekend. Thanks for the info.

Madd - maybe i missed it in your posts but you are using the ford duraspark ignition and not a MSD 6 AL? Just wanted to double check. Also, have heard of the actual ignition switch going bad on our cars.

Yea it wass the duraspark with MSD distributor but I am in the process of changing to the MSD 6AL to take advantage of the rev limiter. I had a 6A laying in the garage which I thought was a 6AL that I was going to swap when I got the car but it ran so good with the duraspark I blew it off. I run into this issue and go to install my spare box and find it is the 6A and since I have to rewire would rather just go with the 6Al and rev limiter. MSD indicated it was fine to run the duraspark.

I guess most mount the msd under the glove compartment but I remeber my old one msd in my bdr buzzing so I may mount in the engine compartment. Hope to get back to it this weekend. I have no doubt this will resolve the issue.

Go with the 6ALN box. It's a little bit more money but much more reliable. I have had a few 6aL boxes fail but never a 6ALN box. Mount it in the passenger foot box under the glove box. You can even mount the 6ALN up-side down with no problems.:)

McVette

I mounted my 6AL under passanger foot well. it gets warm, so i always leave the passanger side fresh air vent open no matter how cold it is. I completely removed the Duraspark unit. I have had the carbon button issue in the distributor cap fail (common issue) and i cross my fingers the 6AL wont give me trouble.

McD00, I've had my MSD fail almost immediately after install. Is there another brand that you would recommend? Is the 6ALN potted in urethane or epoxy for vibration? BTW, its good to still have you around. I miss you so much. :p

I have an electrical problem flow chart that I have laminated. I should scan and post it.

R

Ron,
Here is the info on the 6ALN box.....

The MSD 6ALN not only uses the Nascar mandated Weathertight connector on it but is also full potted with a clear material to protect the unit from high vibrations and still allow for visual inspection by the sanctioning body. You can use the MSD Billet Distributor, PN 8582, but in order to plug it into the MSD 6ALN you will need the MSD Harness, PN 8866, that adapts the distributors connector over to the 6ALN connector. I would use the MSD Blaster HVC Coil, PN 8252. The peak current on that coil is 300mA versus the Blaster 3 which has 140mA. As for the digital 6, you would get the high speed retard feature on that unit over the 6AL along with a little more spark energy. 135 milliJoules on the Digital 6 versus 105-115 on the MSD 6AL.

Yep, I'm still here, thanks for the kind words. I'm on the 19 step program and getting bettter every day but I still have relapses. One day at a time my freind.

Boy what a mistake trading my cobra for a new damn roof.:CRY:

McVette

I use the 6AL2 with zero issues. I have had them running in two cars for 3 months ( they just came out)